Essais d'épuration des eaux usées de Marrakech par la jacinthe d'eau (Charges organique, bactérienne et parasitologique)

Abstract

Cette étude est destinée à tester expérimentalement les capacités d'épuration des eaux usées par lagunage à macrophytes (jacinthe d'eau : Eichhornia crassipes), sous les conditions climatiques de Marrakech.L'installation fonctionne en continu avec un débit constant à l'entrée de 10 l/min. La charge admise est de 40 g DCO/M2/j.Sous l'aspect de la production de biomasse végétale, les effluents domestiques constituent un bon substrat nutritionnel. Les taux de croissance et les productions obtenues montrent dans l'ensemble une excellent adaptation d'Eichhornia crassipesà ce milieu. Le maximum de biomasse et de productivité ont été obtenu en période estivale et sont respectivement de: 40 kg MF/m2 et 38,6 MS/m2/j. Il s'est avéré également que la jacinthe d'eau est persistante toute l'année sous le climat méditerranéen aride de Marrakech.L'épuration des eaux usées domestiques par lagunage à macrophyles aboutit à des rendements satisfaisants surtout en période estivale où on obtient un abattement de 87 % de la DCO et une réduction de 95 % des MEST.Sur te plan sanitaire, l'abattement de la charge bactérienne exprimée par les bactéries témoins de contamination fécale peut atteindre jusqu'à 2ULog pour un temps de séjour théorique très court (7 jours).Ce système e par ailleurs fourni des abattement de 100 % des oeufs d'helminthes parasites au niveau de l'eau épurée.The aim of the present study is to experimentaly test the capacities of the mater hyacinth (Eichhornia crassipes) in order to purify wastewater under Manakesh climatic conditions.The experiment was carried al wastewater spreading zone of Marrakesh pretraitement.The experimant's installation is made of two lined water yacinth ponds that receive domestic wastewater.The proposed process is a continuous system with a constant flow rate of 10 l/mn. The theoritical retention time was estimated to 7 days. The allowed load is 40 g COD/m2/day. Macrophytic biomass was observed for both ponds during the experimental period (Match, 1986 - February, 1987). Parameters of organic, bacterial and parasitological loads are studied in order to determine the system efficiency under arid climate.Obtained results show the water hyacinth ability to adapt to Marrakesh climatic conditions. The number of plants doubled at 12 days, this is coherent with results obtained by PENFOUND (1956), BOCK (1969), WESTLAKE (1963, 1975) and SCULTHORPE (1967). Maximum biomass level and productivity were achieved during the summer period : 40 kg WW/m2/day and 38,6 g DW/m2/day respectively. Biomass and productivity obtained under arid climate are similar to results obtained by WOOTEN and DODD (1976), and by DINGES (1976) under subtropical conditions, and higher than chose obtained by JOHN (1985) under temperate climate. The growth period of water hyacinth is estimated to 9 months at Marrakesh, 10 months at subtropical climate (WOLVERTON and MC DONALD, 1976) and limited to 6 months under cold climate (COPELLI et al., 1982; DUBOIS, 1983; SAUZE, 1983; DE CASABIANCA, 1985). Temperature is considered as a limit...

Removal processes of indicator organisms and opportunistic pathogens in an anaerobic digester‐constructed wetland system

“…In fact, significantly higher removal E. coli was found in the HF‐CW 2 as compared to the VF‐CW 2 during autumn (96.51 ± 0.66%) and winter (92.49 ± 1.47%) as well as for FC during autumn season (94.63 ± 2.59%) (Table 5). This can be attributed also to the presence of plants which are by their foliage cover shading limiting the penetration of solar radiation and allowing some bacteria to grow (Mandi et al , 1992). Beside the reduction of nutrient in VF‐CW 2 along with reducing bacteria; in fact, FC concentrations were correlated to and concentrations ( r = 0.633; 0.588; P < 0.05), while E. coli bacteria was correlated to the NTK and concentrations ( r = 0.817 and 0.839, respectively; P < 0.01).…”